Chapter 6
Skin and the Integumentary
System
• Composed of several tissues
• Maintains homeostasis
• Protective covering
• Retards water loss
• Regulates body temperature
• Houses sensory receptors
• Contains immune system cells
• Synthesizes chemicals,
including Vitamin D
• Excretes small amounts of
waste
Layers of Skin
• Epidermis
• Dermis
• Subcutaneous layer
Epidermis, Dermis, & Basement Membrane
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Epidermis is subdivided into layers of stratified
squamous epithelium
Dermis is made up of connective tissue, epithelial tissue,
smooth muscle tissue, nervous tissue, and blood.
Basement membrane is anchored to the dermis by short
fibrils and separates these two layers of skin
Epidermis
• lacks blood vessels
• keratinized
• thickest on palms and soles (0.8-1.4mm)
• melanocytes provide melanin
• rests on basement membrane
• stratified squamous
Epidermis
Layers of Epidermis
• stratum corneum
• stratum lucidum
• stratum granulosum
• stratum spinosum
• stratum basale
Layers of the Epidermis
Skin Changes: Rashes
Chicken Pox
Shingles
Lyme Disease
Impetigo
Melanocytes and Pigment Granules
All people have the same number of
melanocytes in their skin
Albinism: Lack of Melanin
Paul Bettany in Columbia Pictures' The
Da Vinci Code - 2005
THE ALBINO MONK?
Dermis
• on average 1.0-2.0mm thick
• dermal papillae
• binds epidermis to underlying
tissues
• irregular dense connective tissue
• muscle cells
• nerve cell processes
• blood vessels
• hair follicles
• glands
Subcutaneous Layer
• hypodermis
• loose connective tissue
• adipose tissue
• insulates
• major blood vessels
Hair Follicles
• epidermal cells
• tube-like depression
• extends into dermis
• hair root
• hair shaft
• hair papilla
• dead epidermal cells
• melanin
• arrector pili muscle
Grey’s Anatomy
With age, a
loss of
melanin in hair
can lead to
grayness.
EXAMPLES
OF HAIR
COLOR
VARIATION
Everyone
except albinos
have various
amounts of
melanin in
their hair.
Red Heads
have iron
pigment
(trichosiderin)
Nails
• protective coverings
• nail plate
• nail bed
• lunula
6-9
Sebaceous Glands
• usually associated with hair
follicles
• holocrine glands –
disintegrating cell and its
contents for the secretion
• secrete sebum
• absent on palms and soles
Sweat or Sudoriferous Glands
• widespread in skin
• deeper dermis or hypodermis
• eccrine glands – types of
merocrine gland that secrete fluid
(sweat) product released through
the cell membrane
• aprocrine sweat, ceruminous
(wax), & mammary (milk)
glands – types of aporocrine
glands that secrete cellular
product and portion of the free
ends of cells
Regulation of Body
Temperature
Problems in Temperature
Regulation
Hyperthermia – abnormally high body temperature
Human Body
o
Temperature = 37 C
o
or 98.6 F.
Hypothermia – abnormally low body temperature
Skin Color
Genetic Factors
Physiological Factors
• varying amounts of
• dilation of dermal blood
melanin
vessels
• varying size of melanin
• constriction of dermal blood
granules
vessels
• albinos lack melanin
• carotene
• jaundice
Environmental Factors
• sunlight
• UV light from sunlamps
George Hamilton – sun
• X rays
worshiper?
The Tan Man at The University of Kansas
http://www2.ljworld.com/news/2006/may/03/hes_still
_tan_after_all_these_years/?city_local
Healing of Cuts
Healing of Burns
First degree burn – superficial partial-thickness
(epidermis damaged)
Second degree burn – deep partial-thickness (epidermis
& dermis damaged)
Third degree burn – full-thickness (epidermis, dermis,
& accessory skin structures)
• autograft (self-transplant)
• homograft (temporary transplant from donor)
• various skin substitutes
• extensive scars
Rule of Nines
Life Span Changes
• Scaly skin
• Age spots
• Dermis becomes reduced
• Loss of fat
• Wrinkles
• Sagging
• Sebaceous glands secrete
less oil
• Melanin production slows
• Hair thins
• Number of hair follicles
decrease
• Impaired nail growth
• Sensory receptors decline
• Inability to control body
temperature
• Less vitamin D production
Life Span Changes - Skin
Clinical Application
Acne Vulgaris
• most common skin disorder
• sebum and epithelial cells clog glands
• produces whiteheads and blackheads (comedones)
• anaerobic bacteria trigger inflammation (pimple)
• largely hormonally induced
• androgens stimulate sebum production
• treatments include antibiotics, topical creams, birth control pills
Common Skin Disorders
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Athlete’s foot – tinea pedis or ringworm fungal infection of the foot.
Birthmark – congenital blemish or spot on the skin.
Boil – bacterial infection of the skin produced when bacteria enter a hair
follicle.
Carbucnle – bacterial infection, similar to a boil, that spreads into the
subcutaneous tissues.
Cyst – fluid-filled capsule.
Eczema – noncontagious skin rash.
Erythema – reddening of the skin due to dilation of dermal blood vessels in
response to injury or inflammation.
Herpes– characterize by a recurring formations of small clusters of vesicles;
usually caused by herpes simplex virus; contagious.
Keloid – elevated enlarging fibrous scar usually initiated by an injury.
Mole – fleshy skin tumor that is usually pigmented.
Pediculosis – disease produced by an infestation of lice.
Pruritus – itching of the skin.
Pusule – elevated, pus-filled area.
Xeroderma Pigmentosum

Extreme freckling and skin
cancer due to lack of DNA
repair enzymes.
Types of Skin Cancer
Squamous cell
carcinoma –
derived from
epithelial tissue
Basal cell
carcinoma –
derived from
epithelial tissue
Malignant
melanoma –
derived from
melanocytes